CVE-2004-2677 in QwikMail SMTP
Summary
by MITRE
Format string vulnerability in qwik-smtpd.c in QwikMail SMTP (qwik-smtpd) 0.3 and earlier allows remote attackers to execute arbitrary code via format specifiers in the (1) clientRcptTo array, and the (2) Received and (3) messageID variables, possibly involving HELO and hostname arguments.
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Analysis
by VulDB Data Team • 12/30/2024
The vulnerability described in CVE-2004-2677 represents a critical format string flaw within the QwikMail SMTP server implementation, specifically in the qwik-smtpd.c component. This issue affects versions 0.3 and earlier of the QwikMail SMTP daemon, which is a lightweight mail transfer agent designed for simple email handling. The vulnerability stems from improper input validation and handling of user-supplied data within the SMTP protocol processing logic, creating a pathway for malicious remote code execution through carefully crafted format specifiers.
The technical flaw manifests when the SMTP daemon processes incoming email commands and stores user-provided data into internal variables without proper sanitization. Specifically, the vulnerability occurs in three distinct data handling scenarios involving the clientRcptTo array, the Received header variable, and the messageID variable. These variables are populated with data that originates from client SMTP commands such as HELO, EHLO, and RCPT TO, which are standard SMTP protocol exchanges. When the application attempts to format these variables for logging or processing without proper validation, it creates a format string vulnerability that can be exploited by attackers to manipulate memory contents and execute arbitrary code with the privileges of the SMTP daemon process.
The operational impact of this vulnerability is severe as it allows remote attackers to gain unauthorized code execution on systems running vulnerable versions of QwikMail. Attackers can leverage this weakness by sending specially crafted SMTP commands that contain format specifiers in the affected variables, potentially leading to stack smashing, memory corruption, or direct code execution. The vulnerability is particularly dangerous because it operates at the protocol level where attackers can exploit it without requiring authentication, making it a significant threat to email server security. The attack surface includes not only the immediate execution capability but also potential privilege escalation opportunities if the SMTP daemon runs with elevated system privileges.
Security practitioners should address this vulnerability through immediate patching of affected systems, as the QwikMail project is no longer actively maintained and newer versions do not contain this flaw. Organizations should also implement network segmentation and access controls to limit exposure to this vulnerability. The vulnerability aligns with CWE-134, which specifically addresses format string vulnerabilities, and represents a common attack vector that maps to several ATT&CK techniques including T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation. System administrators should conduct thorough vulnerability assessments to identify all instances of the affected software and ensure proper patch management procedures are in place to prevent similar issues in other software components.